PRESENTATION ON CONCRETE AND ITS SCENARIO IN NEPAL

PRESENTED BY:

MAHESH RAJ BHATT SUNDAR ADHIKARI RAJU KHATRI RAM KRISHNA ACHARYA SANJU SHARMA SADANA TIWARI ( 067/BCE) SCHOOL OF ENGINEERING POKHARA UNIVERSITY

During two last decade rapid technological development in concrete have taken place in world.

We are also in rapid developing situation in Nepal.

Concrete have become a major part of construction.

Its importance is increasing day by day. Western and eastern countries have beeen

making concrete of strength. M40, M80, M100 and over too.

Recently Nepal have started using concrete -M25 , M30 and higher one too. I am 23 at now, during these 23

years ,specially in last 10 years, I have seen drastic growth of use of concrete in my side

“DARCHULA” too Which is mountainous district of Nepal.

Currently we have been also in era of special concrete too

example: -ferrocement concrete, - steel fiber reinforcement concrete -polymer concrete -high strength concrete -self compacting concrete -carbon fiber reinforced polymer(CFRP)

In general : An artificially build up stone resulting from hardening of a mixture of cement ,aggregates and water with or without a suitable admixture “Concrete”. In broadest sense : Any product or mass made by the use of cementing medium. Here, medium is product of reaction between hydraulic cement+water

CONCRETE:

Cement + aggregate + water+ admixtures (7-16)% +(75-83)% + (16-18)% = Concrete

CEMENT: Adhesive & cohesive material

Constituents or property of concrete

-Capable of binding together particles into a compact ,durable mass.

Cement= Cao+Sio2 +Al203 +Fe203 +MgO+SiO3+Na2O, K2O+other

OPC ( 33,43,53 grade):- large scale in all general type construction

RHC (Rapid hardening cement)- Not used in mass Concrete Used in road construction RHCE (Extra rapid hardening cement): OPC + Cacl2 (2%) - Road work

Common types and Uses of cement

SRC(Sulphate resisting cement) -Marine condition -Foundation sewage treatment plant

QSC(Quick setting cement) -Underground water construction -Al204+Cacl2+OPC

Blast furnace cement: -Used in mass concrete -blast slag + OPC

Super sulphate cement: -Marine works Low Heat Cement-C2S is more Expansive cement : -Used in grouting anchor bolts High strength cement-Compressive strength higher then the OPC Resident cement : -Very cold area /winter season Patch repairs, Emergency repairs

Typesi)Based on Origin a. Naturalb. Artificialii. Based on sizec. Fined. Coarsee. All in aggregate

Aggregates

iv) Based on shapea. Round (void 33%)b. Irregular( void 35-37%)c. Angular ( void 38-45%)d. Flaky (>0.6d)e. Elongated (>1.8 L)v). Based on unit weight f. Light(1200-2300 kg/m3)g. Normal(2300-2600 kg/m3)h. Heavy (more than 2600 kg/m3)

vi) Based on surface moisture

a. Very very dry (porosity =0)b. Dry aggregate (pore water partly fill and surface dry)c. Saturated surface dry (pore fully water filled)d. Wet or moist (pore full water +surface water also)

-Pure as drinking water -PH value (6 -8)-vital influence in strength-should not contain Na,K,Mg,etc.-in Nepal it is not given well care towards water-water in Terai contains chemicals which are harmful to

concrete

WATER

-Substance other than the basic ingredients -To improve certain properties like rate of hydration,

workability,durability,impermeablility. Types (Commonly used in Nepal)

A. Accelerator (to gain early strength)Example: CaCl2 ,Na2No3, Na2So4, NaoH B. Retarders (slow down chemical process)Example:Gypsum (CaSO42H2O)

Admixture

C. Water proofer (to proof water) Example: vegetable oil , fat, tar

D. Air entraining agent -To increase workability -To reduce bleeding & segregation effect

E. Pigment mixture - Mn,C,Cr203,Fe203

-for colour purpose.

s.n

Grade

Concrete Mix

Types of Construction

1 M10 1:3:6 Mass concrete piers, abutment , massive RCC (currently rarely used)

2 M15 1:2:4 Normal RCC Slab , Beam, Column, Wall ,small span arches

3 M20 1:1.5:3 Water retaining StructureReservoirs, column & pile

4 M25 1:1:2 Long span arches ,highly loaded column

5 M30 ----- Mass concrete foundation

6 M35 ---- Post tension pre-stressed concrete

7 M40 ------ Pre tension pre-stress concrete

Processes are as followa) Storing of cement and aggregateb) batching ( ingridient measurement) - volume batching ,…weight batchingc) Mixing

Manufacturing of Concrete

1. Hand mixing concrete

- Can not proper mixing- Only small amount mix- Traditional system- Strength can not get proper- Commonly used in small projects in rural areas.

Method of mixing of concrete inNepal

-Proper mixing-Large amount concrete can be formed-Small time consume-High strength gain-currently use in Nepal

2.Mixture mixing Concrete

-Computerized method-Minimum time consume-Modern method-Strength proper maintain-but coastly-also adopted in Nepal in Some special projects

3.Ready mixing Concrete

d) Transportation i) pan transportation ii) wheel barrow iii) bucket and ropeway iv) Belt conveyer v) Truck mixer and damper vi) Pump and pipeline dischargee) Placing layer=15-30 cm =35-45 cm in mass work height of pouring<1.5 m

F) compaction:-5% air bubble reduces 30% strength of concrete-10% bubble reduces 50% strength of concrete i) hand compaction ramming , Tamping , Hammeringii) Mechanical compaction(vibrator) internal vibrator( beam, column, slab , retain wall)Table vibrator( pre cast unit)External vibrator(through formwork)Surface vibrator(slab , road , bridge)Pan vibrator…… small repairs,concrete floor

Vibrator placing

g) curing: - to make compacted concrete wet - to gain maximum strength Water curing Membrane curing Heat apply (steam using) Chemical curing

CaCl2, NaCl …

to absorb water

Segregation control on bucket filling

Various test on Concrete

a. Workability Test (slum test, compaction test)b. Bleeding & Segregation testc. Air content testd. Compressive strength test -Cube test -Cylindrical teste. Tensile strength test

1. Normal concrete All civil Constructione.g residential , public , commerical buildings Mass constructionExample: Dams,Reservoi

CONCRETE USED IN NEPAL

Mass Construction Example:-

Dams,Reservoirs,Bridges,Barrage,Weirs,Canal Road ,Retaining wall

Dam of middle Marsyngdi HP

Intake of middle marshyandi HPP

SETTLING BASIN OF SIKTA IP

Large Span bridge Compressive strength(1100-6700 kg/cm2)

2.High Strength concrete

- Used in Rail way steeper - Liquid storage tank - Heavy bridge girder

We are waiting till now to prestrength concrete

3.Pre Strength Concrete

1. Concrete technology M.S.Shetty2. Concrete technology B.L.Gupta & Amit Gupta3. Objective guides for civil engineers D. Prasad4. http://www.slideshare.net/maheshrajbhatt

THANK YOU!!!!!!!!!!!!

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